Laser cutting system

ABSTRACT

A laser cutting system has a specially designed frame that allows the laser cutting head to be mounted to the underside of a cross beam for a more efficient movement. The frame is further designed so as to allow the accessing of the work area of the laser cutting system along three different directions. The movement of the laser cutting head for fabricating a sheet placed in the work area of the laser cutting system is effected by a process that takes into consideration a number of parameters and determined data all of which are interpolated for generating optimal movements to further enhance the operating efficiency of the laser cutting system. The laser resonator of the laser cutting system of the instant invention is configured to have a telescopic system that maintains the density and power of the laser beam by auto focusing the same so that optimum cuts can be effected irrespective of whichever area of the worksheet is to be fabricated. A special design worktable in the working area of the laser cutting system provides support for the worksheet.

FIELD of the INVENTION

[0001] The present invention relates to a laser cutting system that hasnew designs at least with respect to its frame, its laser outputmechanism, the process of outputting the laser for fabricating aworksheet, and the worktable system to which the worksheet is placed.

BACKGROUND of the INVENTION

[0002] Flying optic laser cutting systems are known. However, the priorart systems tend to have a number of shortcomings that limit their speedand efficiency. Some of these shortcomings result from, for example, thedesign of the frame that supports the cutting head of the laser cuttingsystem, the design of the cutting mechanism itself, the way in which thecutting process is effectuated, the limited way in which a machine maybe installed and, once installed, the limited accessing of the machineby the operator.

[0003] The laser cutting system of the instant invention aims to improveon every aspect of the aforenoted shortcomings of current laser cuffingsystems by, specifically, providing a new frame for the system, animproved laser cutting mechanism, and a more efficient process ofeffecting cuffing. In addition, the laser cutting system of the instantinvention is provisioned with a worktable system that enhances thecutting of a worksheet placed thereon, as well as for evacuating anydust and/or exhaust gases resulting from the fabricating of theworksheet efficiently away from the laser cutting system.

SUMMARY of the INVENTION

[0004] The present invention laser cutting system is built on a framethat has a cross beam supported by two structures. The cross beam isdesigned to have a trapezoidal structure for movably supporting a lasercutting head that hangs therefrom. The laser cutting head in turn ismounted to a base member that has arms extending in a directionperpendicular to the longitudinal axis of the cross beam. As aconsequence, the cutting head can move along the longitudinal axis ofthe cross beam as well as the longitudinal direction along the axis ofthe arms extending from the base member. To effect the movement of thebase member bidirectionally along the longitudinal axis of the crossbeam, a linear drive mechanism, in the form for example of a magnetdrive, may be used. A linear drive may also be used for moving thecutting head along the direction of the extending arms of the basemembers. For the movement of the cutting head along the verticaldirection, a servomotor is mounted to the base member, or morespecifically the skeleton frame of the base member to which the cuttinghead is mounted, so that the cutting head can be moved in a directionperpendicular to the respective longitudinal axes of the cross beam andthe extending arms.

[0005] The cross beam of the frame of the laser cutting system issupported, at both ends, by respective support structures, which may beunitary structures. One the structures is configured to have a borethrough which exhaust gases and/or dust particles resulting from thefabricating of a worksheet by the laser beam output from the cuttinghead may be vented away from the laser cutting system. The other of thesupport structures is configured to have an opening through whichworksheets may be conveyed to or removed from a support table, such asfor example a worktable or a cassette placed underneath the cross beam.The worksheets may also be conveyed to/from the laser cutting systemfrom either side of the cross beam in a direction perpendicular to thelongitudinal axis of the cross beam. To provide further rigidity for theframe of the laser cutting system, two truss members connect the supportstructures at their respective bases.

[0006] To control the movement of the laser cutting head, a processormeans, such as for example a computerized numerical controller (CNC), isprovided in a housing positioned relative to the frame. The CNC, inaddition to controlling the respective movements of the various drivemotors that move the cutting head along the various directions, alsocontrols the outputting of the laser beam to the cutting head by thelaser generator, which is also positioned adjacent and/or relative tothe frame.

[0007] For the laser cutting system of the instant invention, the laserbeam output from the laser beam generator, or resonator, is reflected bya number of mirrors with the focal point of the laser beam forfabricating the particular material of the worksheet to be focused by amotor mechanism internal to the cutting head. To maintain the distancerelated to the widening or focusing of the axial symmetric laser beam,the laser generator of the inventive laser cutting system has atelescope mechanism, positioned within the laser generator itself, thatworks cooperatively with the output coupler of the laser resonator formaintaining the density and the power of the laser beam to constantvalues for a predetermined distance, so that the power of the laser beamrequisite for effectively fabricating the worksheet is maintained forevery portion of the worksheet. The telescope mechanism has two mirrors.One is the output coupler from the laser resonator. The other is thelens that moves relative to the output coupler. The lens is drivenrelative to the coupler by a motor, which is controlled by software ofthe system according to some preset parameters. These parametersinclude, among other things, the distance separating the lens from thesheet material, i.e. the focusing lens distance.

[0008] Such auto-focusing of the laser beam is done automatically by acognizance of a predetermined distance that the laser beam is to beoutput, the type of material being fabricated, and the type oftelescopic mechanism to be used. Moreover, by taking into considerationthe actual length of the laser beam and by dividing the maximum useablelength of the laser beam into a number of zones, i.e., differentquadrants or sectors, the focal point of the laser beam may becorrected. The focus of the laser beam for the different areas of theworksheet may be adjusted by moving the laser cutting headbidirectionally along its vertical axis to maintain respective optimalfocal points for worksheets of different materials.

[0009] To compensate for the deficiencies inherent in the differentareas of the worksheet which may be due to their respective locationswith reference to the center of the worksheet, the worktable or cassetteonto which the worksheet is placed has its areas divided into a numberof portions each with correction factors determined empirically, so thatsuch correction factors may be taken into account when a particularlocation of the worksheet which corresponds to the location on theworktable to which that portion of the worksheet superposes is to befabricated by the laser beam output from the cutting head. Thesecorrection factors are stored in a memory that may be part of the CNCcontroller.

[0010] With respect to the way in which the laser beam output from thelaser generator is to be directed, a number of reflective mirrors areused. To enhance the alignment process, unlike the prior art systemsthat require extensive removal and reassembly of the various mirrors foralignment of the laser beam, the reflective mirrors of the instantinvention laser cutting system are configured such that alignment caneasily be effected by the removal of a single one of the mirrors.Further, the reassembly of the mirror into the system does not requireany further realignment of the laser beam. This is done by configuringthe opening of the mirror holder to have a dimension large enough toallow the removal of the mirror while leaving the mirror holder fixed tothe support of the device and allowing the laser beam to freely pass.

[0011] The laser cutting head being used with the laser cutting systemof the instant invention, but for a number of modifications, could beany cutting head that is sold by a number of manufacturers. One of theimprovements of the cutting head of the instant invention is theprovision of a servomechanism, via feedback, for automatically adjustingthe focus lens inside the cutting head so as to enable the automaticadjustment of the focus point for different types of materials that maybe fabricated by the laser beam output from the cutting head. Anotherimprovement of the cutting head of the instant invention is theprovision of a partition window somewhere within the cutting head forisolating the focusing lens from particles that may ricochet against thefocusing lens when the worksheet is being pierced or cut by the laserbeam. This is particularly true when the laser process is not stable orwhen the parameters for cutting are not set properly. Such partitionmeans may be in the form of a diamond window that has the properties ofbeing translucent so as to allow the laser beam to pass therethrough aswell as having the hardness for withstanding the impacts of thericocheting particles. Other partition windows that have the samequalities as a diamond window may also be used.

[0012] To enhance the fabrication of a worksheet, the movement of thecutting head and the directing of the laser beam thereto are controlledby the CNC in a process that takes into consideration the distanceseparating a location on the worksheet for which work is being done to anext location on the worksheet to which the next piercing by theworksheet is to be effected. To effect the optimal movement of thecutting head from one location to the next, variables such asacceleration and deceleration of the cutting head, the height of thecutting head with respect to the cutting sheet, or the focal point forthe material to which the worksheet is made of, are taken intoconsideration. The movement of the cutting head relative to theworksheet may be termed a “ping pong” effect in that the cutting headmoves in an optimal manner from point to point for piercing variousholes and cuts on the worksheet.

[0013] The worktable onto which the worksheet is placed is made up of aframe, in the shape of a cassette, that is movable in directionsperpendicular to the longitudinal axis of the cross beam. The movementof the cassette is effected on a couple of rails, or guides, onto whichthe cassette rides. Within the cassette there are a number of strips,each having a number of bores formed therealong extending along thelength of the cassette. A number of brackets extend in a directionperpendicularto the strips at predetermined positions along thecassette. These brackets each have a number of equally spaced slotsformed therealong. A plurality of ribs are fitted to equally distancedslots of the brackets so that the ribs and the strips that have thebores are alternated throughout the cassette along its longitudinaldirection. The ribs each are formed with a number of contiguous teeth atits top portion. Into each bore of each strip a pin is inserted. Theplane that is formed by the tips of the pin is higher, although not bymuch, than the plane that is formed by the tip of the contiguous teethof the ribs. Thus, it is the tip of the pins that support the worksheeton the cassette. If the worksheet flexes, or when the worksheet is beingcut, the tips of the contiguous teeth of the ribs would provide supportfor those portions of the worksheet that fall below the plane formed bythe tips of the pins.

[0014] By being able to roll along the rails, the cassette is movablebetween a location under the cross beam for the fabrication of aworksheet placed thereon, and a location that is away from the frame ofthe laser cutting system, so that the finished worksheet may be removed,and be replaced by a to be fabricated worksheet.

[0015] The cassette is placed over a suction frame structure that has anumber of sections each adaptable to provide vacuum to a correspondingportion of the cassette. Thus, by activating the particular section ofthe suction base, particles resulting from the fabrication of theworksheet by the laser beam are suctioned away and vented through thebore at one of the support structures of the frame away from the lasercutting system.

[0016] It is therefore an objective of the present invention to have aframe designed for providing a more efficient way of mounting a cuttinghead for a laser cutting system.

[0017] It is another objective of the present invention to provide alaser cutting system that has an improved laser resonator having meansthat can provide auto-focusing.

[0018] It is yet another objective of the present invention to providean improved cutting head for a laser cutting system that does notrequire its focusing lens to be replaced as often as those inconventional laser cutting heads.

[0019] It is still another objective of the present invention lasercutting system to provide a process of more efficiently moving thecutting head.

[0020] It is still yet another objective of the present invention toprovide a worktable that enhances the fabrication of a worksheet placedthereon by a laser beam.

[0021] It is therefore an overall objective of the present invention toprovide a flying optic laser system that operates in a way that is moreefficient than prior art laser cutting systems.

BRIEF DESCRIPTION of the DRAWINGS

[0022] The above mentioned objectives and advantages of the presentinvention will become apparent and the invention itself will be bestunderstood by reference to the following description of an embodiment ofthe invention taken in conjunction with the accompanying drawings,wherein:

[0023]FIG. 1 is a perspective view of the frame structure of the lasercutting system of the instant invention;

[0024]FIG. 2 is a second perspective view of the frame structure of thelaser cutting system of the instant invention;

[0025]FIG. 3 is a perspective view of the base member that is to bemounted to the cross beam of the FIGS. 1 and 2 frame structure;

[0026]FIG. 4 is a perspective top view of the FIG. 3 base member;

[0027]FIG. 5 is a bottom view of the frame structure of FIG. 2;

[0028]FIG. 6 is a perspective view of the frame structure of FIGS. 1 and2 having mounted thereto the base member of FIG. 3;

[0029]FIG. 7 is a perspective view of the FIG. 5 frame structureillustrating the underside of the cross beam and the support structuresof the FIGS. 1 and 2 frame structure;

[0030]FIG. 8 is a cross sectional view of the FIG. 1 frame structurewith the base member of FIG. 3 shown in relationship to the cross beam;

[0031]FIG. 9 is a perspective view of the frame structure of FIG. 1covered by the appropriate doors and having attached thereto the cabinethousings for the laser resonator and the processor controlling unit;

[0032]FIG. 10 is another perspective view of the FIG. 9 frame structureshowing the opening at one of the support structures;

[0033]FIG. 11 is yet another perspective view of the laser cuttingsystem of FIG. 10 showing access to the work area of the system by meansof the opening at one of the support structures and also at one side ofthe laser cutting system;

[0034]FIG. 12 is a perspective sectional view of the cross beam and thebase member that is movably mounted to the cross beam;

[0035]FIG. 13 is another perspective view of the cross beam and the basemember, as viewed from another end of the cross beam;

[0036]FIG. 14 is a perspective view of the frame structure and the basemember and the laser resonator mounted adjacent to the frame forillustrating the path of the laser beam from the laser resonator to thecutting head of the laser cutting system of the instant invention;

[0037]FIG. 15 is a plan view illustrating the laser resonator, theinside components of the laser resonator, and the alignment of the laserbeam from the laser resonator, as well as the path of the laser beam tothe cutting head;

[0038]FIG. 16 contains a frontal view of the reflective mirror of thelaser cutting system of the instant invention used for alignment of thelaser beam;

[0039]FIG. 17 is a perspective view of the reflective mirror of thelaser cutting system of the instant invention;

[0040]FIG. 18 is a disassembled view of a laser cutting head;

[0041]FIG. 19 is an assembled view of a portion of the laser cuttinghead of FIG. 18 illustrating in particular the placement of a partitionlens for protecting the focusing lens of the laser head;

[0042]FIG. 20 is an illustration of the focusing of the laser beam atthe various partitioned locations of a worktable;

[0043]FIG. 21 is an illustration of the routing of a laser beam and thecooperation between the telescopic device and the output coupler in thelaser generator for regulating the focusing of the laser beam;

[0044]FIG. 22 is an illustration for enhancing the understanding of howthe cutting head of the instant invention laser cutting system is moved;

[0045]FIG. 23 is a plan view of a worksheet with various holes thereinfor further illustrating the cutting head movement of the instantinvention;

[0046]FIG. 24 is a flow chart illustrating the process of moving thelaser cutting head of the instant invention;

[0047]FIG. 25 is a sectional perspective view of the various componentsthat make up a worktable cassette;

[0048]FIG. 26 is an enlarged perspective view of a corner section of thecassette of FIG. 25;

[0049]FIG. 27 is a front view of a portion of the cassette, and how itrides on the rails as shown in FIG. 25;

[0050]FIG. 28 is a perspective view of the base of the worktable of theinstant invention laser cutting system that is adaptable to providesuction at the various portions of the cassette placed thereover;

[0051]FIG. 29 is a second perspective view of the base shown in FIG. 28;

[0052]FIG. 30 is an end view of the laser cutting system of the instantinvention with the cassette and the suction provided base all shown inrelative relationship with the frame structure of FIGS. 1 and 2; and

[0053]FIG. 31 is an illustration of the auto-focusing feature of theinstant invention system.

DESCRIPTION of the PREFERRED EMBODIMENTS

[0054] With reference to FIG. 1, a frame structure of the laser cuttingsystem of the instant invention is shown. This frame structure 2 has across beam 4 being supported by two support structures 6 and 8. Supportstructure 8, as best shown in FIG. 2, comprises two parts, namely anupper portion 8 a resting on a base portion 8 b. It should be noted,however, that upper portion 8 a and base portion 8 b may actually beformed as a unitary structure. Or for that matter, upper portion 8 a mayactually be an extension of cross section 4. Be that as it may, baseportion 8 b of support structure 8 has an opening 10 through whichaccess can be gained to the area of the frame underneath cross beam 4and between support structures 6 and 8. This area may simply be referredto as the work or working area. As further shown in FIGS. 1 and 2, theworking area can also be accessed from either side of cross beam 4, suchas for example via directional arrows 12 and 14. To provide exhaustventing (which will be discussed in detail later) a bore 16 is providedin support structure 6.

[0055] With respect to cross beam 4, note that it has been designed inthe form of a trapezoid, with the base being wider than the top. SeeFIGS. 12 and 13. The inventors have found that such trapezoidal designprovides an efficient support of the cutting head of the presentinvention laser cutting system. To provide additional rigidity to frame2, two truss support beams 16 and 18 fixedly couple support structures 6and 8 at their respective bases.

[0056] A frame for supporting a worksheet processing apparatus such asfor example a laser cutting head is shown in FIGS. 3 and 4. Inparticular, a base member 20 has fixedly mated thereto an arm 22 thathas equal portions extending from either side of base member 20. As bestshown in the top perspective view of FIG. 4, base member 20 has boltedto its top, which is the portion that is to be movably coupled to theunderside of cross beam 4, a number of mounts 24 that are to be coupledto the bearings of a linear guide, to be discussed laser. Also coupledto the top of base member 24 are two sets of support members 26 and 28to which respective drive motors in the form of magnetic drivesmanufactured for example by the Siemens or Krauss Maffei Companies, aremounted. The magnetic drives may also be referred to as linear drives.Two center support members 30 coupled to the top of base member 20provide mounting support for a linear scale that measures the distancetraversed by base member 20 with reference to the longitudinal axis ofcross beam 4. More on that later.

[0057] The underside of arm 22 is best shown in FIG. 3. As illustrated,there are two guiding rails 32 and 34 extending substantially the entirelength of arm 22. Movably mounted to guide rails 32 and 34 is a lasercutting head support frame 36 that has a front portion, designated 38,that is configured to accept a conventional cutting head made by anumber of manufacturers including such as for example the PrecitecCompany of Germany. The movement of frame 36, and therefore the lasercutting head mounted thereto, may be effected by a linear drive motorsuch as for example the aforenoted magnetic drives or some otherequivalent motor so that cutting head support frame 36 is movablebidirectionally, per indicated by bidirectional arrows 40.

[0058] As noted with respect to the discussion of base member 20 in FIG.4, there are two coil sliders of the linear drive motor that are coupledto support members 26 and 28. These coil sliders, which may be simplyreferred to as the linear motor or magnetic drives, would move betweenmagnets 40 a, 40 b and 42 a and 42 b, when base member 20 is movablycoupled to the underside of cross beam 4. See the bottom view of frame 2in FIG. 5. Further shown to be coupled to the underside of cross beam 4are linear guides 44 a and 44 b, which work cooperatively with mounts 24of base member 20.

[0059] In addition, a linear scale 46 that extends substantially alongthe entire length of the underside of cross beam 4 works cooperativelywith the scale mounted to support members 30 of base member 20 toprovide an indication of where along the longitudinal axis of cross beam4 the base member is at any moment. Such linear scale is manufactured bythe Heidenhain company of Germany. For our discussion, the movement ofbase member 20 along the longitudinal axis of cross beam 4 is deemed tobe along the x direction. Similarly, the bidirectional movements ofcutting head frame 36 along the longitudinal axis of arm 22 mounted tobase member 20 are deemed to be movements along the y direction. Thesame linear drive that may be purchased from either the Siemens or theKrauss Maffei Companies of Germany could be used for both the x and they movements of base member 20 along cross beam 4, and frame support 36along the length of arm 22, respectively.

[0060]FIG. 6 illustrates perspectively base member 20 being mounted tothe underside of cross beam 4 of frame 2. FIG. 7 is yet anotherperspective view of base member 20 being movably mounted to theunderside of cross beam 4 and is therefore movable along the xdirection, as indicated in FIG. 6. Frame 36 to which the laser cuttinghead is being mounted likewise is movable along the y direction so thatby controlling the respective movements of base member 20 along crossbeam 4 and frame member 36 along arm 22, the laser cutting head mountedto frame 36 can be moved to any portion of the area underneath crossbeam 4 defined between support structures 6 and 8.

[0061]FIG. 8 is a cross-sectional view of the frame structure 2 of theinstant invention. In addition, it shows base member 20 beingdisassembledly associated relative to the underside of cross beam 4.Frame 36is further shown being disassociated from arm 22. For thepurpose of illustrating the relationship between frame 36 and the lasercutting head, note that laser cutting head 48 is movably mounted to thefront of frame member 36, while a servomotor 50 that drives cutting head48 along the direction as indicated by directional arrows 52, i.e., thez axis, is shown to be mounted to the back of frame member 36.

[0062]FIGS. 9, 10 and 11, in combination, show the three openings, oncethe laser cutting system has been equipped with the appropriate coveringand doors, that could be used to gain access to the work area of thelaser cutting system defined between the two support structures 6 and 8.In particular, as shown in each of FIGS. 9, 10 and 11, a cabinet orhousing 52 is provided adjacent to support structure 6. Housing 52 maybe used to contain the electrical components such as for example the CNCprocessing unit that controls the respective operations of the lasercutting system. Also provided adjacent to support structure 6 is anothercabinet or housing 54 that houses the laser beam resonator or generatorof the system. The generation of the laser beam, and its path inrelation to frame 2, will be discussed later. For the time being, itsuffices to note that FIGS. 9 and 11 show two doors 56 a and 56 b thatare adaptable to be opened so as to allow the accessing of a workpieceor worksheet 58 placed on top of a worktable, or cassette, 60 within thework area defined between support structures 6 and 8.

[0063]FIG. 10, on the other hand, illustrates the fact that the insideof the work area defined between support structures 6 and 8 may beaccessed through opening 10 by raising a door 62. This is useful forthose instances where perhaps a conveyor may be provided at opening 10to convey worksheet 58 into and/or out of the working area of lasercutting system 2. FIG. 10 moreover shows two additional doors 64 a and64 b movably fitted to the other side of cross beam 4 and adaptable tobe opened so as to allow access to the working area of the laser cuttingsystem. Note that doors 56 a, 56 b and 64 a, 64 b may each be replacedby respective single doors 56 and 64. Also, a relatively smallermaintenance door, not shown, may be provided at either side of thesystem of the instant invention.

[0064] In sum, frame 2 of the laser cutting system is designed such thatit enables the accessing of its working area from three directions, eachindependent of the other. This allows a more efficient utilization ofspace by the user, insofar as the laser cutting system may be placed atsuch a location that gaining access to the working area of the systemthat otherwise would have posed a problem by other laser cutting systemscould easily be done with the laser cutting system of the instantinvention.

[0065] Given the configuration of the frame of the instant invention,when doors 62, 56 a, 56 b and 64 a, 64 b are closed, as per requiredduring the operation of the laser system, passages that allow air toflow into the interior of the system per paths indicated by arrows 3 and5 are established. Thus, air from the environment are sucked into theinterior of the system for replacing the air that is sucked out by thevacuum created in the work table or cassette, the details of which willbe discussed with respect to FIGS. 28 and 29, infra.

[0066]FIGS. 12 and 13 are respective perspective views of thetrapezoidal cross beam 4 and the mounting thereto at its underside ofbase member 20, and the mounting to arm 22 of base member 20 by lasercutting head 48. FIGS. 12 and 13 in essence illustrate that with theparticular designs of cross beam 4, base member 20 and arm 22, a mostefficient system that enables a fast positioning of cutting head 48 isachieved. This design is quite different from the conventional “gantry”type systems whereby the laser cutting head is mounted to a cross beammounted to support members, which are movable relative to the worktable.

[0067] Further with respect to cross beam 4, insofar as it has an upsidedown trapezoidal cross section, it is found that both of its sides andits underside are enveloped by the air that is being sucked into theinterior of the system via paths 3 and 5. Accordingly, the sucked in airprovides an air shield around the linear drives, and any coveringthereof, mounted to the underside of cross beam 4 and arm 4 to therebyprotect those linear drives or the covering to those drives from beinghit by the debris or particles that result from the fabrication of theworksheet. Additionally, the sucked in air could dislodge dirt thatmight otherwise accumulate at the drives and their covers.

[0068]FIGS. 14 and 15 illustrate the pathway in which a laser beam 66 isoutput from a laser resonator 54 to cutting head 48 and out of itsnozzle 49 for piercing a worksheet. Specifically, inside laser resonatorcabinet 54 a laser resonator 68 would generate a laser beam that isoutput from an optical output coupler 70. The laser beam is thenreflected by mirrors 72 and 74 so as to be emitted at output port 76along the direction indicated by beam path 78. A laser mirror 80 allowsthe laser beam 66 to be routed to a target 82 for alignment purposesand, at the same time, redirects the laser beam 66 along laser path 84to yet another mirror 86 that redirects the laser beam to cutting head48 and out of its nozzle 49, as shown in FIG. 14. Output coupler 70 andother beam mirrors maintain the distance of the laser beam being outputto a predetermined distance that is deemed to be useful, i.e., bymaintaining the requisite density and power for the laser beam to piercea worksheet. The laser generator inside laser cabinet 54 can bepurchased from a number of companies including for example theWegmann-Baasel Company of Germany.

[0069] An improvement to a conventional laser resonator of the instantinvention laser cutting system is the utilization of a telescopic lens88, that is controllable for example by a servomotor such as 90, whichautomatically focuses the laser beam to maintain a constant density andpower for the laser beam for a predetermined distance away from outputport 76. By maintaining a constant density and power for the laser beamfor the predetermined distance, such as for example 5 meters away, thebeam is able to perform optimal piercing and cutting of a workpiece. Asshown in FIG. 15, such predetermined distance may extend from the outputof output port 76 to substantially the full length of the area betweensupport structures 6 and 8, SO as to accommodate the movement of lasercutting head 48 mounted to base member 20 along the length of cross beam4.

[0070] The telescopic lens system may comprise a telescopic lens 88 thatis movable along the length of the laser beam so as to provide afocusing effect to maintain constant the density and power of the laserbeam output from window 76. In place of a movable telescopic lens suchas 88, a mirror type telescope system may also be used. In conjunctionwith the servomotor such as 90, a threaded screw or other types of drivemechanism may be used for moving telescopic lens 88 relative to outputcoupler 70. Note also that even though resonator cabinet or housing 54is shown not in contact with frame structure 2, in actuality, resonatorcabinet 54 may be physically coupled to frame structure 2, as forexample by links and bolts, so that both laser resonator 68 and framestructure 2 may be moved in unison to thereby maintain the alignment ofthe laser beam with respect to frame structure 2.

[0071] With the telescopic system, auto-focusing of the laser beam, withrespect to the worksheet, can be effected by providing a feedback signalfrom the cutting head to the CNC controller that informs the controllerwhether or not focusing is required. When the feedback received from theCNC controller indicates that indeed focusing is required, the CNCcontroller would send a signal to servomotor 90, or to be more precisevia instructions to the controller of servomotor 90, to move telescopiclens 88 relative to coupler 70 so as to automatically refocus the laserbeam, to thereby maintain constant its density and its power. Theproviding of a feedback of the cutting head to the CNC controller willbe further described with the discussion of the cutting head in FIG. 18.

[0072] Although not shown, there is provided within electronic cabinet52, in addition to CNC controller, at least one memory store (hard disk,tape drive, magnetic memory store, etc.) that contains information inregard to the focal movements during fabrication of the worksheet, suchas for example piercing or cutting, so that lens 88 can be repositionedrelative to output coupler 70 each time the laser beam reaches its stoppoint. This allows the focal point of the laser beam to be adjusted evenduring the fabrication of the worksheet. Thus, the auto-focusingfunction of the laser cutting system of the instant invention has threedifferent subfunctions. These include: (1) to change the focal pointaccording to the selection of the type of worksheet material; (2) tochange the focal point on line according to the length of the laser beamof the laser cutting system; and (3) to effect focal movements duringpiercing so as to have the maximum energy at the point where actualpiercing takes place. Subfunction 2 is meant to provide compensationforthe beam divergence when the laser beam path is somewhat longer thanthe optimal predetermined beam path, and subfunctions 3 is used toreduce the piercing time.

[0073] As for the types of materials that may be affected by the focalpoint changes, note that depending on the type of material to be cut,the focal point may actually be located negatively, positively or atzero, with respect to the worksheet. This is because the focal point ofthe laser beam may actually be somewhat above, below or at the surfaceof the worksheet. For example, a normal steel worksheet that has athickness of approximately 1-6mm requires that the focal point be at thesurface of the worksheet. Alternatively, a normal steel worksheet thathas a thickness of approximately 8-20mm requires that the focus of thelaser beam be approximately 1 mm above the surface of the worksheet.Furthermore, a stainless steel worksheet with a thickness ofapproximately 1-10mm requires that the focal point be negative, i.e. thefocal point is below the bottom surface of the worksheet beingprocessed. As for a worksheet that is made of aluminum having athickness of 1-6mm, the focus of the laser beam is deemed to be atoptimum at approximately {fraction (1/3)} of the thickness of theworksheet below the surface of the worksheet. Worksheets made of othermaterials such as for example wood and other synthetics require lessstringent focal points. Of course, other parameters and known factorssuch as for example the power of the laser beam and the density of thelaser beam may also need to be taken into account to effect the positionof the focal point.

[0074] During fabrication such as for example piercing, to enable thesystem of the instant invention to continuously adjust the focal pointon line, a set-up table or memory store that contains the start pointand the stop point is provided to the CNC controller for repositioningthe cutting head along the z direction to effect auto-focusing. For theinstant invention, this is done by taking into consideration the actuallength of the laser beam (from the laser resonator output to the cuttinghead along the x and y directions), and comparing it with the maximumpredetermined laser beam length. The maximum useable length of the laserbeam in turn is divided into a number of quadrants, or zones. Each ofthe zones is provisioned (in the set-up table or memory store) with aparticular correction factor so that when the actual laser beam lengthfalls within that quadrant, the correction factor, be it a negative orpositive number, is used to adjust the focal point of the laser beam.

[0075] For further illustration, see FIG. 31 which shows the maximumpredetermined length of the laser beam, designated as 220. The maximumlength of the laser beam in turn is divided into a number of sectors,quadrants or zones 222 a-222 h etc. A correction factor, such as forexample 0-0.5mm in zone 222 a, is provided in each of the zones. Alsoshown in FIG. 31 is the actual length of the laser beam, designated forexample by 224 a and 224 b, representing the x and y axes of the beampath, respectively. Thus, for the exemplar laser beam 224 shown in FIG.31, given that it ends at zone 222g, a correction factor of 3-3.5m, beit positive or negative, is added to the focal point by refocusing thelaser beam via, for example, the movement of telescopic lens 88 relativeto output coupler 70 (as shown in FIG. 14). Note that even though thecorrection numbers in zones 222 are shown as positive numbers, inactuality, these numbers are integers that could be either positive ornegative numbers, depending on the type of materials being fabricated,so that the auto-focusing of the focal point may be effected eitherabove the worksheet, below the worksheet, or at the surface of theworksheet, as previously discussed. Thus, there may be stored in theset-up table a plurality of the exemplar series of zones as shown inFIG. 31, one for each type of material of the worksheet that is to befabricated.

[0076] Another improvement of the present invention laser cutting systemis the use of a particular type of mirror at a location such as 80 forenabling laser beam 66 to be aligned per target 82, without having tohave the complete mirror assembly disassembled as required by most ofthe prior art laser cutting systems. Specifically, as shown in FIG. 16,the improved laser mirror 80 of the instant invention has a blockportion 91 that has a notch 92 a and another notch 92 b. By thusproviding the respective notches, a laser beam such as 66 that is outputfrom output window 76 can directly pass through block 91 and be alignedwith target 82. Thus, the only thing that needs to be done with respectto reflective mirror 80 for the laser cutting system of the instantinvention is the removal of the actual mirror itself, such as 94 shownin FIG. 17, without having to remove the mirror block 91 from thesystem. Contrast this with most of the prior art laser cutting systemsthat require the removal of the mirror blocks from the system in orderto align the laser beam, which means that after the alignment of thelaser beam, the mirror block further has to be reassembled. Oftentimes,such reassembly would cause misalignment of the laser beam. For theinstant invention, the fact that the mirror block 91 is not removedmeans that once the laser beam is aligned, it remains aligned as it isonly mirror 94 that is removed from reflective mirror assembly 80.

[0077] As shown in FIG. 17, mirror 94 is matably mounted to mirror block91 and fixedly coupled thereto by means of bolts 96. As is well known,mirror 94 has complemented thereto circulation tubings such as 98 thatallow cooling fluid be directed to the mirror (actually behind casing100), so as to maintain the temperature of the mirror constant as it isbeing impacted by the laser beam. By providing cooling to the mirror,the mirror is prevented from warping to thereby ensure the integrity ofthe laser beam.

[0078]FIG. 18 shows a conventional type of cutting head that can bepurchased from a number of manufacturers including for example thePrecitec Company of Germany. As shown, cutting head 48 has a collisionprotection mounting 100 that is coupled to frame member 30 for absorbingany impact cutting head 48 may have with frame member 30 when the formeris driven in a vertical direction along the z axis. A top mounting 102provides a coupling to frame member 30 to allow a conduit through whichthe laser beam may pass. An upper focusing part 104 of laser head 48enables the user to adjust the focus of the laser beam, per moving thefocusing lens, which is held by a lens holder 106, for adjusting thefocal point of the laser beam.

[0079] The focusing of the laser beam may also be effected in adirection substantially perpendicular to the z direction by using acontrol screw 108. In fact, for the laser cutting system of the instantinvention, it is envisioned that the adjustment of the focusing lensbeing held by lens holder 106 be effected by servomotors that take intoaccount the feedback provided by a capacitance or non-contacting sensor110 that senses the distance separating the tip of the laser cuttinghead from the top surface of the worksheet. The signal from theelectrode 110 in turn is sensed and forwarded to electrode cable 112,which is shown, per dotted line 114, to be inserted into the sensorportion 116 of the cutting head. Electrode cable 112 in turn isconnectable to a preamplifier 118 that in turn is electrically connectedto the CNC controller for relaying thereto whatever signals are sensedby sensor 110, to thereby establish the feedback for determining how farthe tip of the cutting head is from the surface of the worksheet.

[0080] Cutting head 48 further includes an adapter portion 120 to whichlower insert portion 116 is matable with. Adapter 120 in turn is matedwith upper part 104, so as to enclose lens holder 106. Cutter head 48further includes a ceramic non-conductive tip 112 that is mated to thetip of insert portion 116. A nut 114 secures ceramic portion 112 to thelower insert 116. A nozzle electrode 118, which is fitted to ceramicportion 112, completes the laser cutting head 48. It is throughelectrode nozzle 118 that the laser beam is output for fabricating theworksheet. For those instances where non-metallic worksheets are beingfabricated, a tactile electrode or contacting sensor 120 is used inplace of nozzle electrode 118.

[0081]FIG. 19 illustrates the improvement to the cutting head shown inFIG. 18 for the laser cutting system of the instant invention. Inparticular, prior to the instant invention, lens 122, which is held bylens holder 106, in effecting the focusing of the laser beam 66, isassisted by the input of lasing gas within the space designated 124.This is all well and good so long as the debris, particles and partsthat result from worksheet 58 being pierced or cut by laser beam 66 doesnot ricochet back into chamber 24 and end up impacting the lower surfaceof lens 122. Given that the cost of focusing lens 122 is high and itssensitivity is of relative importance, by exposing lens 122 to potentialimpacts caused by ricocheting debris or particles, the life expectancyof lens 122 is shortened. In fact, one of the major cost of a lasercutting system is the often replacement of lens 122.

[0082] The laser cutting head of the instant invention overcomes thisshortcoming by interposing a partition window 126 between focusing lens122 and nozzle 118. Partition window 126 may be made of diamond or someother translucent material that has the same qualities of diamond, i.e.,hardness and resistance to scratching, and the characteristic ofallowing laser beam 66 to pass therethrough without much effect. Notethat although partition window 126 is shown to be located at the lowerpart of lower portion 120, it could in fact be placed within lowerinsert 116, which is held in place by nut 114. Given that the space fromthe tip of electrode nozzle 118 to partition window 126 is much lessthan the volume provided in chamber 124, the amount of lasing gasprovided to input 128 that acts in conjunction with laser beam 66 topierce the worksheet can be substantially reduced. Partition window 126therefore achieves the dual objectives of prolonging the life of lens122 as well as decreasing the amount of lasing gas required for coactingwith the laser beam for piercing the worksheet.

[0083] With reference to FIG. 20, the maintenance of the optimal powerfor the laser beam that works hand in hand with the auto-focusing of thefocal point is described. As is known conventionally, when output fromthe laser resonator, the laser beam is never quite parallel. In otherwords, the laser beam tends to be slightly diverted so that it wouldappear such as the beam 66 shown in FIG. 20. That notwithstanding, aswas mentioned previously, a portion of the laser beam nonetheless isuseful, provided that the diameter of that portion of the laser beam iskept to be substantially parallel so as to contain substantially thesame diameter and the same density. For laser beam 66 shown in FIG. 20,assume for the moment that such parallel portion exists at the portionof the beam designated 130. Thus, so long as focus lens 122 (cuttinghead 48 is not shown forthe sake of simplicity) is moved within thedistance designated by 130, an accurate focal point is provided for aworksheet placed on worktable 60. But as it can be seen in FIG. 20,worktable 60 in fact extends beyond distance 130 whereby the density ofthe laser beam is maintained constant. What this means is that the focalpoint of the laser beam, for example 132, would be off for the portionof the laser beam that diverges. This is equivalent to the laser beamlosing power because of its distance from the laser resonator 68. Forthe instant invention laser cutting system, to compensate for this lossof power, worktable 60 is divided into a number of predetermined zonesor sections each having correction data that may be obtained empiricallyon a prototype laser cutting system that has undergone a great number oftesting.

[0084] For the exemplar system shown in FIG. 20, therefore, supposeinstead of being directed to an area 60 j of worktable 60 (assuming area60 j is the area on the worksheet placed over worktable 60 at whichlaser beam 60 is piercing), focusing lens 122 is to be focused onto theportion of the worksheet that superposes over section 60 k. At thispoint, note that laser beam 66 has substantially diverged. From theempirical data collected and stored in the memory store which isretrievable by the CNC controller, suppose that at area 60 k ofworktable 60, there is provided a correction data of 0.10 mm. Given thatand the fact that the CNC controller gets a feedback from thecapacitance sensor 110 (FIG. 18) of the distance separating the cuttinghead from the surface of the worksheet, appropriate correctionalmovement may be output by the CNC controller to instruct the servomotorto reposition focusing lens 122 with the appropriate correction datawhich, in this instance, is 0.10 mm toward the worksheet (assuming thatthe correction is plus 1.0 mm in this instance). Therefore, by dividingthe worktable into different zones, areas or sections having theirrespective coordinates in terms of the x and y axes, the worktable inessence is divided into a number of matrixes each having its owncorrection data that can be used to correct any divergence of the laserbeam, to therefore maintain a laser beam that has substantially the samepower density for every area on the worktable onto which a worksheet maybe placed.

[0085]FIG. 21 illustrates in a simplified schematic format thecontrolling of the adjustment of the laser beam by the CNC controller.This corresponds to the laser resonator portion shown in FIG. 15 inwhich the beam width and density of laser beam 66 can be controlled bythe interaction between output coupler 70 and telescopic lens 88, whichis driven by a servomotor 90. The instructions for activating servomotor90 for driving telescopic lens 88 in relation to output coupler 70 areprovided by the CNC controller, which in turn receives feedback fromcutting head 48.

[0086] The way in which the cutting head is moved relative to aworksheet for the instant invention laser cutting system is effected bya “ping pong” process whereby an optimal movement of the cutting head iscalculated for moving it from one location to a next location on theworksheet. In particular, with reference to FIGS. 22 and 23, note that aworksheet may have already cut thereinto a number of holes or cuts. Theping pong process of the instant invention allows the laser cutting headpositioned at a first location, for example at 130, to be moved to anext location, for example 132, at an optimal rate. This is done by theCNC controller, in conjunction with an interpolation process, based onthe determination of a number of things.

[0087] One of the items that is determined is the focal distance thatseparates the nozzle from worksheet 58, for example the distancedesignated 134. Another item that needs to be determined is the distanceseparating the location where the cutting head is and the next locationwhere the cutting head needs to be for the next fabrication process onworksheet 58. In other words, the CNC controller has to know thedistance separating points 130 and 132. For the interpretation process,it is assumed that the shorter the distance between 130 and 132, theless likely the cutting head needs to be elevated along the z directionas indicated in FIG. 22. On the other hand, if the distance separatingpoints 130 and 132 is great, and if cutting head 48 were to be elevatedsufficiently above worksheet 58, the speed at which cutting head 48 maybe moved between the two locations can be incrementally increased. Suchelevation of cutting head 48 is indicated in FIG. 22 by, for example,dotted lines 136 and 138. Note that 138 indicates that cutting head 48is to be moved further away from worksheet 58 inasmuch as the nextlocation to which it is to be moved is further than location 132. Ofcourse, it is understood that the higher cutting head 48 is elevatedfrom worksheet 58, the less the chance that any flexing of worksheet 58could cause it to come into contact with cutting head 48.

[0088] For those instances where the worksheet already has prefabricatedholes, either through previous punching or cutting, when laser head 48encounters such a hole, such as for example 140 shown in FIG. 22, due tothe capacitance sensing of the distance separating the surface ofworksheet 58 and the nozzle electrode of cutting head, prior to theinstant invention ping pong process, the cutting head would naturallymove down towards worksheet 58 since it has no knowledge that hole 140is present; and in certain instances, if a predetermined stop distancehas not been programmed into the CNC controller, cutting head 48 wouldactually come into contact with worksheet 58. The movement process ofthe instant invention eliminates such inadvertent contact by instructingcutting head 48 to move from a first location to a next location by anelevation vector such as 139, distance permitting between the locations.In other words, cutting head 48 would, similar to the actions of a pingpong ball, bounce from one location to the next.

[0089] To obtain the optimal movement for cutting head 48, a number ofparameters are programmed into the CNC controller so that the variousoperations for fabricating a hole or cut in a worksheet aresynchronized. To wit, the movement of the laser cutting head 48 issynchronized with the outputting of the laser beam from the laserresonator. For example, when the laser cutting head has finishedpiercing a hole in a first location, just before cutting head 48 is tobegin its movement to the next location, the laser beam is turned off atthe laser resonator. And just prior to cutting head 48 reaching the nextlocation, for example 132, the laser resonator would begin to generatethe laser beam so that the output of the laser beam is timed such thatit begins to pierce worksheet 58 as soon as cutting head 48 has stoppedat location 132 and the focal point separating cutting head 48 andworksheet 58 is at the appropriate height. The same process is effectedwith the respect to the movement of cutting head 48 to its nextlocation. For example, as soon as the piercing or cutting of worksheet58 is completed at location 132, cutting head 48 begins its movement tothe next location at the predetermined elevation and speed, and thelaser resonator begins to turn off the laser beam. This process isrepeated until all locations on the worksheet that need to be fabricatedare done.

[0090]FIG. 23 provides an illustration of the relationship between thedistance separating different locations and the speed with which cuttinghead 48 is moved. For example, the distance separating locations 142 to144, as represented by the shown circles or holes, is greater than thedistance separating locations 144 and 146. Accordingly, cutting head 48may be elevated to a higher height and moves faster from location 142 to144. Insofar as location 144 to 146 is separated by a shorter distance,the elevation of cutting head 48, if any, would be lower than theelevation of cutting head 48 between locations 142 and 144, as ittravels from location 144 to 146. An optimal time nonetheless ismaintained for cutting head 48 to move from location 144 to location 146insofar as the distance separating those locations is relatively short.Putting it simply, there is no need to elevate cutting head 48 if thedistance separating a first location to a second location is small, forexample 5 mm. Thus, by determining the coordinates in which lasercutting head has to move and the spatial relationship between thevarious locations, an optimal movement for moving cutting head 48 fromlocation to location superposing the worksheet can be interpolated.

[0091] A flow chart illustrating the process of moving the laser head ofthe instant invention is given in FIG. 24. The process begins bydetermining the focal distance between the laser cutting head and theworksheet at step 150. At or about the same time, a determination ismade of the distance separating the various locations per step 152.Further, a determination is made on the distance separating the nozzlefrom the worksheet per step 154. These determined data are taken intoconsideration with various predetermined parameters which, in additionto those mentioned previously, may also include the weight of the lasercutting head, the acceleration and deceleration that are needed formoving the laser head and stopping it, and other data such as forexample how long it takes the laser beam to be turned on and off andtravel to the cutting head, etc. Using these various parameters anddetermined data, the optimal movement for the laser cutting head isinterpolated per step 156. Thereafter, the instructions to the cuttinghead for the optimal movement are generated per step 158. With thoseinstructions, the CNC controller can instruct the motor mechanism suchas for example the linear drives and the servomotors to move the lasercutting head from one location to the next, per step 160. The laser beamis generated and provided to the cutting head per step 162 right beforethe cutting head gets to its next lactation. Thereafter, the output ofthe laser beam is synchronized with the movement of the laser cuttinghead so that the laser beam is output as soon as the movement of thecutting head has stopped, per step 164. Step 164 takes into account thetermination of the laser beam as the laser cutting head begins itsmovement to the next location. At step 166, a determination is made ofthe next location to which the cutting head is to be moved. And adetermination is made per step 168 on whether all cuts have beeneffected on 5 the worksheet. If no, the process continues. If all cutsindeed have been made on the worksheet, the process stops.

[0092] With reference to FIG. 25, worktable 60 that is placed in theworking area of the laser cutting system of the instant invention isshown. Worktable 60 may also be referred to as a cassette. As shown,worktable 60 has a frame 170 that 10 comprises two long sides 172 a and172 b, and two short sides 174 a and 174 b.

[0093] Frame 170 is movably mounted on two rails, or slides, 176 and178. Insofar as worktable or cassette 60 is movable along the ydirection, the worksheets placed thereon (either before fabrication orafterwards), can be retrieved readily from either side of the lasercutting system, as shown for example in FIGS. 10 and 11, 15 as frame 170can be readily moved through doors 56 and door 64 at respective sides ofthe laser cutting system of the instant invention. As best seen in FIG.27, frame side 174 b rolls per roller 180 along rail 178 while frameside 174 b slides along rail 178.

[0094] Further with reference to FIG. 25, it can be seen that there area number 20 of support brackets 182 extending along the x direction offrame 170. With specific reference to FIGS. 26 and 27, a plurality ofstrips 184 each extending along they direction of frame 170 from side172 a to 172 b are shown. These strips are supported by base members186, only a few of which are shown in frame 170 in FIGS. 26 and 27.Formed along the length of each of strip members 25 184 are acorresponding number of bores 188 into which a number of pins 190 arefixedly mated to. Each of pins 190 has a replaceable tip that is made ofa soft metal such as for example copper or brass. Further mounted toframe 170 is a plurality of ribs 194. These ribs are mounted to selectedslots 196 of the support brackets along the length of frame 170 at the xdirection, and are interspersed with the plurality of strips having thebores through which pins 190 are mounted. Each of ribs 194 has an upperor top portion that is shaped with a number of contiguous teeth 198.

[0095] Thus, frame 170 has alternate rows of pins and teeth along its xdirection for supporting a worksheet, such as for example 58 placedthereon. In fact, tips 192 of pins 190 form a plane that is slightlyhigher than the plane that is formed by the tips of the various teeth198 of ribs 194. The fact that the pins form a higher support plane thanthe teeth means that the worksheet is mainly supported by the pins. Thisis desirable insofar as there is less of an area of the worksheet thatis being supported. The fact that tips 192 of pins 190 are replaceablemeans that when the tip of a pin is worn out, such as for example bybeing repeatedly impacted by the laser beam, only that tip needs to bereplaced, as there is no need to replace the entire pin. The ribs areused to support those portions of the worksheet that are either cut fromthe worksheet or have sagged somewhat.

[0096]FIGS. 28 and 29 are respective perspective views of the base ontowhich worktable or cassette 60 is mounted. Base 200 is made of aplatform 202 that is divided into a number of sections 204 a-204 f.Platform 202 in turn is mounted to two tubular chutes 206 and 208 bymeans of legs 210. Chutes 206 are hollow ventilation chutes that has anumber of openings 212 formed therealong which are adaptable forreceiving a tube 214 that connects the opening to an opening of acorresponding one of sections 204 a-204 f. Tubes 214, only one of whichis shown for the sake of simplicity, is movable vertically by means of acorresponding hydraulic cylinder 216 for connection to its correspondingsection. By providing vacuum in chute support 206, a vacuum is createdat the appropriate sections 204 so as to suction the dust particlesand/or exhaust gases or fluids that result from the piercing or cuttingof the worksheet by the laser beam. The dust particles thus suctionedare collected and vented through chute output 218, which in turn isconnected to vent 16 (FIGS. 1 and 2), so that the fall out dustparticles are collected and removed from the work area of the lasercutting system. By synchronizing the cutting of the worksheet, thelocation of the worksheet where the cut is being effected, and thesection of base 200 activated for suctioning, most, if not all, of thedust particles and waste gases from the laser beam cutting of theworksheet are removed.

[0097]FIG. 30 is a cross-sectional view of the laser cutting system ofthe instant invention. In essence, it shows the relative positioning ofthe various components of the system by overlaying the frame structurewith the worktable and the base to which the worktable is movablysuperposed.

[0098] Inasmuch as the present invention is subject to many variations,modifications and changes in detail, it is intended that all mattersdescribed throughout this specification and shown in the accompanyingdrawings be interpreted as illustrative only and not in a limitingsense. For example, even though the work processing apparatus describedhereinabove relates to a laser cutter, it should be appreciated thatother work processing apparatus such as for example a punch or a cuttermay also utilize the frame structure of the present invention.Accordingly, it is intended that the invention be limited only by thespirit and scope of the hereto appended claims.

Claims
 1. A method of moving a laser beam outputting device relative toa worksheet for fabricating said worksheet, said device superposing oversaid worksheet, a focal distance being established between said deviceand said worksheet, the focal distance varies in response to changes inthe vertical distance separating said device and said worksheet, saidmethod comprising the steps of: a) determining the focal distanceseparating said device and said worksheet; b) determining the distanceseparating a location on said worksheet above which said device is andthe next location on said worksheet above which said device is to bemoved to; c) determining the optimal movement for said device to getfrom said location to said next location; d) using said optimal movementto move said device to said next location after said location is piercedby a laser beam output from said device; and e) repeating steps a to duntil all locations to be pierced on said worksheet are pierced. 2.Method of claim 1, wherein said step c further comprises the step of: atleast taking into consideration the distance separating said locationand said next location and the focal distance from said device to saidworksheet for effecting the optimal piercing of a hole in said worksheetby said laser beam.
 3. Method of claim 2, wherein said step c furthercomprises the step of: changing the height said device superposes oversaid worksheet in accordance with the distance separating said locationfrom said next location; and varying the speed with which said device ismoved from said location to said next location in proportion to thedistance separating said device from said worksheet.
 4. Method of claim1, further comprising the step of: outputting said laser beamsubstantially at the same time that said device has stopped at said nextlocation.
 5. Method of claim 1, further comprising the step of:deactivating said laser beam at substantially the same time or justprior to the movement of said device to said next location.
 6. Method ofclaim 1, wherein said step a comprises the step of: provisioning saiddevice with a sensor for continuously monitoring the vertical distanceseparating said device from said worksheet.
 7. Method of claim 3,wherein said changing step comprises the steps of: increasing the heightsaid device superposes over said worksheet, up to a maximum height, inresponse to the distance separating one location from an other locationon said worksheet; and increasing the speed of moving said device fromsaid one location to said other location the higher said devicesuperposes over said worksheet and/or the further said one location isfrom said other location.
 8. Method of claim 1, wherein said step cfurther comprises the steps of: interpolating the acceleration speed andthe deceleration speed of said device by taking into consideration atleast the path that separates one location from an other location andthe vertical distance that separates said device from said worksheet. 9.Method of claim 8, wherein said interpolating step further comprises thesteps of: accelerating said device away from said one locationsubstantially immediately after the appropriately pierced cut has beeneffected at said one location on said worksheet; moving said device in avertical direction to an optimal height away from said worksheet if itis determined that said other location is of sufficient distance awayfrom said one location to warrant the moving of said device to saidheight; decelerating the speed of said device before said device reachessaid other location so that said device substantially reaches said otherlocation at the end of its deceleration; and outputting said laser beamto pierce said worksheet as soon as said device reaches said otherlocation.
 10. Method of claim 1, further comprising the steps of:providing a work table whereon said worksheet is placed; andpartitioning the space on said work table whereon said worksheet isplaced into a number of areas each having a set of parameters forcompensating any irregularities peculiar to that area that couldconceivably affect the optimal piercing of holes by said laser beam tothe portion of said worksheet overlying that area.
 11. A laser cuttersystem, comprising: a laser beam outputting device movably positionedrelative to a worksheet for outputting a laser beam to fabricate saidworksheet, said device superposing over said worksheet; motor means fordriving said device; and processing means for controlling said motormeans for moving said device to locations over said worksheet forfabricating said worksheet, said processing means calculating themovements required for optimally moving said device between saidlocations by a) establishing a focal distance that varies in response tochanges in the vertical distance separating said device and saidworksheet between said device and said worksheet; b) determining thefocal distance separating said device and said worksheet; c) determiningthe distance separating a location on said worksheet above which saiddevice is and the next location on said worksheet above which saiddevice is to be moved to; d) determining the optimal movement for saiddevice to get from said location to said next location; e) using saidoptimal movement to move said device to said next location after saidlocation is pierced by said laser beam output from said device; and f)repeating steps a to d until all locations to be pierced on saidworksheet are pierced.
 12. System of claim 11, further comprising: awork table whereon said worksheet is placed; wherein said processingmeans partitions the space on said work table whereon said worksheet isplaced into a number of areas each having a set of parameters forcompensating any irregularities peculiar to that area that couldconceivably affect the optimal piercing of holes by said laser beam tothe portion of said worksheet overlying that area.
 13. System of claim11, wherein said processing means, in calculating step d, further takesinto consideration at least the distance separating said location andsaid next location and the focal distance from said device to saidworksheet for effecting the optimal piercing of a hole in said worksheetby said laser beam.
 14. System of claim 11, wherein said processingmeans, in calculating step d, further instructs said motor means tochange the height said device superposes oversaid worksheet inaccordance with the distance separating said location from said nextlocation, and to vary the speed with which said device is moved fromsaid location to said next location in proportion to the distanceseparating said device from said worksheet.
 15. System of claim 12,wherein said processor means instructs said motor means to change theheight of said device by increasing the height said device superposesover said worksheet, up to a maximum height, in response to the distanceseparating one location from an other location on said worksheet in, andto increase the speed of moving said device from said one location tosaid other location the higher said device superposes over saidworksheet and/or the further said one location is from said otherlocation.
 16. System of claim 11, further comprising: a sensorprovisioned to said device for continuously monitoring the verticaldistance separating said device from said worksheet.
 17. System of claim11, wherein said processing means, in calculating step d, furtherinterpolates the acceleration speed and the deceleration speed of saiddevice by taking into consideration at least the path that separates onelocation from an other location and the vertical distance that separatessaid device from said worksheet.
 18. System of claim 17, wherein saidprocessing means further instructs said motor means to move said deviceby: accelerating said device away from said one location substantiallyimmediately after the appropriately pierced cut has been effected atsaid one location on said worksheet; moving said device in a verticaldirection to an optimal height away from said worksheet if it isdetermined that said other location is of sufficient distance away fromsaid one location to warrant the moving of said device to said height;decelerating the speed of said device before said device reaches saidother location so that said device substantially reaches said otherlocation at the end of its deceleration; and outputting said laser beamto pierce said worksheet as soon as said device reaches said otherlocation.
 19. System of claim 1 1, wherein said processing means furthercontrols the outputting of said laser beam substantially at the sametime that said device has stopped at said next location.
 20. System ofclaim 11, wherein said processing means further deactivates said laserbeam at substantially the same time or just prior to the movement ofsaid device to said next location.